Feel free to use this as long as you credit me! Also you can delete the unlock all, and choose when to unlock costumes in your game, just add a 'replace item no ____ of Unlocked? with Unlocked.
All code by me, fish art by scratch, buttons by me. You can use as many costumes as you like for the skins, and you can customise the buttons as well. This is simply to showcase what it could look like.